Final conclusions:
After a total config wipe and fresh setup of plex, streaming HEVC/HDR to Chromium browser web player or Xbox One works flawlessly. However after adding additional libraries and playing some other content, Plex seems to break and forget how to properly utilize the GPU, only doing about 3% GPU usage for the transcode, and going into buffer loops.
Possible maybe when a 4K screen is attached to Xbox, it will work as direct play and skip the need for transcode, but playing a large file size 4k video and expecting the transcode to 1080p beyond the first 15 minutes of a fresh plex config… not gonna happen.
No means found to address the original topic of thread, as in starting a fresh config and then pulling over metadata, collections etc. from old config.
